Administration mechanism for a medicament delivery device

ABSTRACT

The present disclosure relates to an administration mechanism for a medicament delivery device having a movable sleeve, and a delivery member cover having a distal end portion configured to receive the movable sleeve. The delivery member being configured to be linearly displaceable between a first position and a second position relative to the movable sleeve, wherein the distal end portion has an end face defining a guide surface and the movable sleeve has a radially outwards extending first follower structure configured to cooperate with the guide surface when the delivery member cover is moved from the first position towards the second position, causing the movable sleeve to rotate.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of Ser. No. 16/315,282, filedJan. 4, 2019, which is a U.S. National Phase Application pursuant to 35U.S.C. § 371 of International Application No. PCT/EP2017/065820 filedJun. 27, 2017, which claims priority to European Patent Application No.16179476.3 filed Jul. 14, 2016. The entire disclosure contents of theseapplications are herewith incorporated by reference into the presentapplication.

TECHNICAL FIELD

The present disclosure generally relates to medical devices. Inparticular, it relates to an administration mechanism for a medicamentdelivery device and to a medicament delivery device comprising such anadministration mechanism.

BACKGROUND

Medicament delivery devices such as auto-injectors are very common onthe market as they facilitate for users to manage medicamentadministration.

An example of a medicament delivery device is disclosed in WO2011/123024 A1. The medicament delivery device has a tubular housing anda tubular activation member, displaceable from an extended position to aretracted position relative to the housing, and configured to bereturned to the extended position. The medicament delivery device alsohas a tubular operation member configured to cooperate with the tubularactivation member. The tubular activation member has first co-actingmeans in the form of two oppositely arranged radially inwards extendingprotrusions, and the tubular operation member has second co-acting meansinteractively connected to the corresponding first co-acting means. Inparticular, the second co-acting means include grooves on the outersurface of the tubular operation member and the radial inwards extendingprotrusions are adapted to be guided within a respective groove, forcingthe tubular operation member to rotate when the tubular activationmember is axially moved from the extended position towards the retractedposition. Moreover, the tubular operation member has locking means, e.g.a respective flexible tongue, in the grooves, which lock a respectiveone of the radially inwards extending protrusions when the tubularactivation member returns from the retracted position towards theextended position and the radially inwards extending protrusions moveover the respective tongue. In this manner, the tubular activationmember is locked from displacement as it returns to the extendedposition after medicament administration.

SUMMARY

The radially inwards extending protrusions of the tubular activationmember may extend radially inwards to such an extent that when themedicament container is introduced into the housing during assembly, themedicament container, in particular a distal end flange thereof, maymomentarily engage with the protrusions as the medicament container ismoved forward in the housing. This may damage the protrusions so thatthey become weakened, which may result in that the protrusions break ifthe medicament delivery device, with the tubular activation member beingin the locked position, is dropped accidentally, and the tubularactivation member absorbs the impact. This could lead to the tubularactivation member being moved into the housing, towards the retractedposition thereof thereby exposing the delivery member.

In view of the above, a general object of the present disclosure is toprovide an administration mechanism for a medicament delivery devicewhich solves or at least mitigates the problems of the prior art.

A first aspect of the present disclosure provides an administrationmechanism for a medicament delivery device, where the administrationmechanism has a movable sleeve, and a delivery member cover having adistal end portion configured to receive the movable sleeve. Thedelivery member cover is configured to be linearly displaceable betweena first position, a second position and return to a third position,which may be the same as the first position, relative to the movablesleeve. The distal end portion of the delivery member cover has an endface defining a guide surface and the movable sleeve has a radiallyoutwards extending first follower structure configured to cooperate withthe guide surface when the delivery member cover is moved from the firstposition towards the second position, which in turn causes the movablesleeve to move.

The guide surface is an end surface of the delivery member cover. Inparticular, the guide surface extends between the outer surface of thedelivery member cover and the inner surface of the delivery membercover. The guide surface hence defines the radial thickness, or wallthickness, of the delivery member cover. The guide surface, whichenables rotation of the movable sleeve, will therefore not extendradially beyond the inner surface of the delivery member cover. As aresult, there will be no risk of momentary engagement with a medicamentcontainer when a medicament container comprising the administrationmechanism is assembled.

According to one embodiment the movable sleeve comprises a radiallyoutwards extending second follower structure and the distal end portionof the delivery member cover has a cut-out configured to receive theradially outwards extending second follower structure, wherein theradially outwards extending second follower structure is configured tocooperate with a wall of the cut-out, causing rotation of the movablesleeve when the delivery member cover is moved from the second positiontowards the first position.

It may thereby be possible to detect movement of the movable sleeve bothduring administration, when the delivery member cover moves from thefirst position to the second position, and also when drug delivery hasbeen finalised and the delivery member cover moves from the secondposition to the first position, due to the further rotation. It maythereby be possible to register both drug delivery and finalisationthereof, for example by means of a sensor or switch configured to detectrotation of the movable sleeve.

According to one embodiment the radially outwards extending secondfollower structure has a triangular shape and the wall of the cut-out isa slanting surface.

According to one embodiment the movable sleeve has a lock structureconfigured to be received by the cut-out and configured to preventmovement of the delivery member cover when returned to the firstposition from the second position.

According to one embodiment the radially outwards extending firstfollower structure has an oblique surface configured to cooperate withthe guide surface.

According to one embodiment the radially outwards extending firstfollower structure is a circumferentially extending rib.

According to one embodiment the movable sleeve has a lock structure andwherein the delivery member cover has a cut-out configured to receivethe lock structure when the movable sleeve is rotated by the deliverymember cover.

According to one embodiment the cut-out has an axially extendingelongated portion configured to allow linear displacement of thedelivery member cover relative to the lock structure when the lockstructure is arranged in the cut-out.

According to one embodiment the lock structure is flexible radiallyinwards and the delivery member cover has a through-opening configuredto receive the lock structure when the delivery member cover is returnedfrom the second position to the first position.

According to one embodiment the through-opening is arranged distallyfrom and axially aligned with the axially extending elongated portion ofthe cut-out.

According to one embodiment the lock structure and the through-openingform a snap lock function.

According to one embodiment the lock structure is arranged proximallyrelative to the radially outwards extending first follower structure.

According to one embodiment the guide surface is a cam surface.

One embodiment comprises a first resilient member configured to bias thedelivery member cover towards the first position.

There is, according to a second aspect of the present disclosureprovided, a medicament delivery device comprising: a housing having aproximal opening, an administration mechanism according to the firstaspect, configured to be received by the housing, wherein in the firstposition the delivery member cover is configured to extend from theproximal opening, and wherein the delivery member cover is configured tobe rotationally locked relative to the housing.

Generally, all terms used in the claims are to be interpreted accordingto their ordinary meaning in the technical field, unless explicitlydefined otherwise herein. All references to “a/an/the element,apparatus, component, means, etc. are to be interpreted openly asreferring to at least one instance of the element, apparatus, component,means, etc., unless explicitly stated otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

The specific embodiments of the inventive concept will now be described,by way of example, with reference to the accompanying drawings, inwhich:

FIG. 1 is a perspective view of an example of a medicament deliverydevice;

FIG. 2 shows an exploded view of the medicament delivery device in FIG.1 ;

FIG. 3 shows a first example of an administration mechanism for amedicament delivery device;

FIG. 4 a shows a side view of the medicament delivery device in FIG. 1prior to activation thereof;

FIG. 4 b shows a side view of the medicament delivery device in FIG. 4 awith the housing removed to expose interior components;

FIG. 5 a shows a side view of the medicament delivery device in FIG. 1during activation thereof;

FIG. 5 b shows a side view of the medicament delivery device in FIG. 5 awith the housing removed to expose interior components;

FIG. 6 a shows a side view of the medicament delivery device in FIG. 1after activation thereof;

FIG. 6 b shows a side view of the medicament delivery device in FIG. 6 awith the housing removed to expose interior components; and

FIG. 7 a shows a second example of an administration mechanism for amedicament delivery device, in particular during one stage of use;

FIG. 7 b shows a second example of an administration mechanism for amedicament delivery device, in particular during one stage of use;

FIG. 7 c shows a second example of an administration mechanism for amedicament delivery device, in particular during one stage of use;

FIG. 7 d shows a second example of an administration mechanism for amedicament delivery device, in particular during one stage of use; and

FIG. 7 e shows a second example of an administration mechanism for amedicament delivery device, in particular during one stage of use.

DETAILED DESCRIPTION

The inventive concept will now be described more fully hereinafter withreference to the accompanying drawings, in which exemplifyingembodiments are shown. The inventive concept may, however, be embodiedin many different forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided byway of example so that this disclosure will be thorough and complete,and will fully convey the scope of the inventive concept to thoseskilled in the art. Like numbers refer to like elements throughout thedescription.

The term “proximal end” as used herein, when used in conjunction with anadministration mechanism, refers to that end of the administrationmechanism which is intended to be pointed towards the injection siteduring medicament administration, when the administration mechanism isproperly installed in a medicament delivery device. The sameconsiderations also apply when referring to any component of theadministration mechanism. The “distal end” is the opposite end relativeto the proximal end. With “proximal direction” and, equivalently,“proximally” is meant a direction from the distal end towards theproximal end, along the central axis of the safety mechanism. With“distal direction” or “distally” is meant the opposite direction to“proximal direction”.

The present disclosure relates to an administration mechanism comprisinga movable sleeve and a delivery member cover configured to cooperatewith each other such that linear movement of the delivery member covertranslates to rotational movement of the movable sleeve. The deliverymember cover has a distal end portion which has an end face. The endface connects the outer surface of the delivery member cover with theinner surface of the delivery member, and is hence a distal end wall ofthe delivery member cover. That dimension of the end face which extendsfrom the outer surface to the inner surface is hence the thickness ofthe delivery member cover. The end face defines a guide surface.

The movable sleeve has a radially outwards extending first followerstructure configured to cooperate with the guide surface of the deliverymember cover. Moreover, the delivery member cover is movable relative tothe movable sleeve, between a first position and a second position. Whenmounted inside the housing of a medicament delivery device, the firstposition corresponds to an extended position of the delivery membercover relative to the housing and the second position corresponds to aretracted position relative to the housing. When the delivery membercover is moved from the first position to the second position, the guidestructure is configured to cooperate with the radially outwardsextending first follower structure, causing rotation of the movablesleeve. The guide surface and the radially outwards extending firstfollower structure may hence be seen to have cam functionality.

FIG. 1 shows an example of a medicament delivery device 1. Theexemplified medicament delivery device 1 is an injector, in particularan auto-injector. The medicament delivery device 1 has a proximal end 1a and a distal end 1 b and comprises an example of an administrationmechanism of the type described above.

Medicament delivery device 1 has a housing 3 and a delivery member cover5, which in FIG. 1 is arranged in the extended position relative to thehousing 3. Linear movement of the delivery member cover 5 from theextended position to the retracted position causes activation of themedicament delivery device 1.

FIG. 2 shows an exploded view of the medicament delivery device 1. Theexemplified medicament delivery device 1 furthermore includes a movablesleeve 6, which together with the delivery member cover 5 forms anadministration mechanism. The medicament delivery device 1 also includesa first resilient member 7, a plunger rod 9, a tubular member 11, asecond resilient member 13, a rod 15, a feedback member exemplified byU-bracket 17, and an end member 19.

The first resilient member 7 is configured to bias the delivery membercover 5 in the proximal direction. Hereto, the delivery member cover 5is configured to be biased towards the extended position relative to thehousing 3. The first resilient member 7 may for example be a spring.

The movable sleeve 6, or rotator, which is tubular, is configured tocooperate with the delivery member cover 5 so that linear displacementof the delivery member cover 5 causes rotation of the movable sleeve 6.Furthermore, the movable sleeve 6 is configured to receive the tubularmember 11.

The tubular member 11 is configured to receive the plunger rod 9 and theU-bracket 17, which is configured to be arranged around the plunger rod9. Furthermore, the second resilient member 13 is configured to bias theplunger rod 9 proximally.

The second resilient member 13 is configured to be arranged around therod 15. The rod 15 hence ensures that the resilient member 13, typicallya spring, maintains its axial elongation during compression andexpansion. The exemplified plunger rod 9 is hollow and configured toreceive the rod 15 and the second resilient member 13. The U-bracket 17has two legs and is configured to receive the plunger rod 9therebetween. The U-bracket 17 has a distal transverse connectionportion which connects the two legs, and forms a distal end of thesub-assembly consisting of the plunger rod 9, the rod 15, the secondresilient member 13 and the U-bracket 17.

The second resilient member 13 is furthermore configured to bias theU-bracket distally, so that when the plunger rod 9 is released from itsaxially locked position and moved forward in the proximal directionduring medicament administration, as will be described below, theU-bracket 17 is released and thrown backwards in the distal direction,causing auditory feedback when impacting with the end member 19.

The tubular member 11 has radially flexible arms 11 a, of which one isshown in FIG. 2 , which in an initial rotational position of the movablesleeve 6, are pressed radially inwards by the inner walls of the movablesleeve 6. The plunger rod 9 has an outer surface provided with recesses9 a, of which only one is shown in FIG. 2 . Each radially flexible arm11 a is configured to engage with a respective recess 9 a when theradially flexible arms 11 a are pressed radially inwards by the movablesleeve 6, in particular by the inner walls thereof. In this manner, theplunger rod 9 is maintained in an axially fixed position as long as themovable sleeve 6 is in its initial rotational position, i.e. itsposition prior to movement of the delivery member cover 5 from theextended, or first, position, towards the retracted, or second,position, which causes rotation of the movable sleeve 6.

The movable sleeve 6 has an inner surface provided with recesses, notshown in FIG. 2 . When the movable sleeve 6 is rotated, these recessesalign with the radially flexible arms 11 a, allowing the radiallyflexible arms 11 a to flex radially outwards, which up until this momenthave been pressed radially inwards by the inner walls of the movablesleeve 6, towards their default position. The radially flexible arms 11a thus disengage from the recesses 9 a. The plunger rod 9 is hencereleased from its axially fixed position, and is, due to it being biasedin the proximal direction by the second resilient member 13 moved in theproximal direction, causing medicament expulsion as it moves proximallyinside the medicament container 21.

FIG. 3 shows the delivery member cover 5 and the movable sleeve 6. Thedelivery member cover 5 and the movable sleeve 6 form or form part of,an administration mechanism 23.

The delivery member cover 5 has means for preventing rotation relativeto the housing 3. Such means may for example be axial ribs or groovesarranged on the outer surface of the delivery member cover 5, configuredto be engaged with corresponding grooves or ribs, respectively, of theinner surface of the housing 3. Alternatively, the means may be arrangedon the inner surface of the delivery member cover 5, configured toengage with an inner structure of the housing 3, for example amedicament container holder.

The movable sleeve 6 may be configured to be axially fixed relative tothe housing 3, or it may be configured to be essentially axially fixedrelative to the housing 3. In the latter case, there may be a playpresent which allows for a certain small axial movement of the movablesleeve 6 relative to the housing 3. The small axial movement, especiallyduring the activation of the medicament delivery device, may beadvantageous because it will reduce or minimize the risk of jamming ornegatively affecting the movement of the movable sleeve 6 due totolerance factors or friction between components.

The delivery member cover 5 has a distal end portion 5 a, and a proximalend portion 5 b. The proximal end portion 5 b has a generally tubularshape, and the distal end portion 5 a has two legs 5 f. The deliverymember cover 5 is configured to receive the movable sleeve 6. Inparticular, the movable sleeve 6 is configured to be arranged betweenthe two legs 5 f such that the inside surface of the distal ends of legs5 f cover a proximal part of the outer surface of movable sleeve 6.

The distal end portion 5 a of the delivery member cover 5, in particulareach leg 5 f, has an end face 5 c defining a respective guide surface 5d. The movable sleeve 6 has a radially outwards extending first followerstructure 6 a. The radially outwards extending first follower structure6 a has a follower surface 6 e. It is to be noted that there may be tworadially outwards extending first follower structures 6 a, each beingconfigured to cooperate with a respective guide surface 5 d. For thepurpose of simplification, only one guide surface 5 d and one radiallyoutwards extending first follower structure 6 a will be discussed in thefollowing.

The guide surface 5 d and the radially outwards extending first followerstructure 6 a are configured to cooperate when the delivery member cover5 is moved from the first position relative to the movable sleeve 6towards the second position. According to the present example, thefollower surface 6 e of the radially outwards extending first followerstructure is an oblique surface in the axial direction, configured tocooperate with the guide surface 5 d when the delivery member cover 5 ismoved from the first position towards the second position relative tothe movable sleeve 6.

The movable sleeve 6 has a radially outwards extending second followerstructure 6 b. The distal end portion 5 a, in particular each leg 5 f,furthermore has a cut-out 5 e which has an open end in the proximaldirection. The cut-out 5 e is configured to receive the radiallyoutwards extending second follower structure 6 b when the movable sleeve6 is rotated, i.e. while the radially outwards extending first followerstructure 6 a and the guide surface 5 d cooperate. Furthermore, thecut-out 5 e has a wall 5 g, according to the present example an inclineddistal end wall, configured to cooperate with the radially outwardsextending second follower structure 6 b when the cut-out 5 e hasreceived the radially outwards extending second follower structure 6 band the delivery member cover 5 is released and returned towards thefirst position, causing further rotation of the movable sleeve 6.Hereto, the movable sleeve 6 is subjected to a first rotational motionwhen the delivery member cover 5 is moved from the first position to thesecond position and to a second rotational motion when the deliverymember cover is moved from the second position back towards the firstposition. This may be advantageous in that a sensor may be utilised todetect both the commencement of medicament administration by detectingthe first rotational motion, and to detect that medicamentadministration has finalized by detecting the second rotational motion.

The radially outwards extending second follower structure 6 b may have atriangular shape, with one edge of the triangle forming a distal endpoint of the radially outwards extending second follower structure 6 b.The radially outwards extending second follower structure 6 b may thusfollow the inclined distal end wall of the cut-out 5 e such that theradially outwards extending second follower structure 6 b is fullyreceived in the triangular space formed between the inclined distal endwall and the adjacent axial wall of the cut-out 5 e when the deliverymember cover 5 has returned to the first position.

The movable sleeve 6 may also have a lock structure 6 c, extendingradially outwards, configured to lock the delivery member cover 5 in thefirst position upon return from the second position. Hereto, accordingto the example in FIG. 3 , the movable sleeve 6 has a proximallyextending flexible tongue 6 d and the lock structure 6 c is provided ata proximal end portion of the proximally extending flexible tongue 6 d.The lock structure 6 c may be an essentially wedge-shaped radiallyoutwards extending protrusion and having a distally facing obliquesurface 6 f configured to cooperate with the inside surface of thedelivery member cover. The lock structure 6 c may be axially alignedwith and proximally arranged from the radially extending secondfollowing structure 6 b. Due to the radial flexibility of the proximallyextending flexible tongue 6 d, the lock structure 6 c is bent radiallyinwards when the delivery member cover 5 is returned from the secondposition towards to the first position, until the cut-out 5 e allows thelock structure 6 c to flex radially inwards. The lock structure 6 c willthus bear against the proximal wall 5 g of the cut-out 5 e, preventingthe delivery member cover 5 from being moved from the first positiontowards the second position.

With reference to FIGS. 4 a to 6 b , the function of the administrationmechanism 23 will be described in more detail. FIG. 4 a shows a sideview of the medicament delivery device 1 with the delivery member cover5 in the first position relative to the movable sleeve. The deliverymember cover 5 is hence in the extended position relative to the housing3.

FIG. 4 b shows the same state of the medicament delivery device 1 asFIG. 4 a , but with the housing removed, to expose internal componentsincluding the administration mechanism 23. In the state shown in FIG. 4b , the guide surface 5 d has not yet been moved in the distaldirection, and thus no cooperation between the guide surface 5 d and theradially extending first follower structure 6 a has taken place.

FIG. 5 a shows the medicament delivery device 1 in an activated state.The delivery member cover 5 has been displaced distally from the firstposition relative to the movable sleeve 6 towards the second position,exposing the delivery member 25, in this example a needle. The deliverymember cover 5 has hence been moved in the distal direction from theextended position relative to the housing 3 towards the retractedposition.

FIG. 5 b shows the same state as FIG. 5 a but with the housing removed.Here, the guide surface 5 d of the delivery member cover 5 cooperateswith the radially outwards extending first follower structure 6 a, inparticular the follower surface 6 e. As the delivery member cover 5 ismoved in the distal direction, the cooperation between the deliverymember cover 5 and the movable sleeve 6 causes the movable sleeve 6 torotate until the end face 5 c of the delivery member 5 has moved alongthe entire follower surface 6 e.

In the situation shown in FIG. 5 b the radially outwards extendingsecond follower structure 6 b has moved into the cut-out 5 e of thedelivery member. The radially outwards extending second followerstructure 6 b has however at this point not yet cooperated with the wall5 g of the cut-out 5 e. Moreover, the proximally extending flexibletongue 6 d is bent radially inwards by the inner surface of the deliverymember cover 5.

FIG. 6 a shows a state of the medicament delivery device 1 in which thedelivery member cover 5 has returned from the second position relativeto the movable sleeve 6 to the first position, i.e. to the extendedposition relative to the housing 3.

FIG. 6 b shows the same state as FIG. 6 a but with the housing removed.Here, the delivery member cover 5 has been returned, due to its proximalbiasing, to the first position relative to the movable sleeve 6. Theradially outwards extending second follower structure 6 b has thusfollowed the wall 5 g, which is an inclined distal end wall, of thecut-out 5 e. This causes additional rotation of the movable sleeve 6, inthe same direction as the first rotational motion, when the deliverymember cover 5 is returned to the first position. Moreover, theproximally extending flexible tongue 6 d is moved into the cut-out 5 e,causing it to flex radially outwards, whereby the lock structure 6 cextends radially into the cut-out 5 e, bearing against the proximal wallof the cut-out 5. The lock structure 6 c is hence snapped into thecut-out 5 e, preventing the delivery member cover 5 from displacement inthe distal direction from the first or extended position.

The delivery member cover may according to one variation have a weakenedmechanical structure at each leg, proximally from the cut-outs. Thisweakened mechanical structure may for example be obtained by providingone or more through-openings aligned with the cut-out. The weakenedmechanical structure provides a resilience of the delivery member cover,so that in case the medicament delivery device is dropped onto a rigidsurface with the proximal end as the leading edge, the weakenedmechanical structure will provide damping of the force so that theimpact will be lower on the proximal end wall and the lock structure.

The inclination of the follower surface 6 e is a design parameterdependent of the rotation necessary to release the plunger rod 9. Theinclination of the wall 5 g is dependent of the amount of rotationnecessary for detecting further rotation of the movable sleeve, to beable to provide feedback of an end of a drug expulsion.

FIGS. 7 a-7 e show another example of an administration mechanism forinstallation in a medicament delivery device such as medicament deliverydevice 1. Administration mechanism 23′ also includes a delivery membercover 5′ and a movable sleeve 6′, a rotator. Similarly to the firstexample, linear displacement of the delivery member cover 5′ from afirst position relative to the movable sleeve 6′ to a second positionresults in cooperation between the delivery member cover 5′ and themovable sleeve 6′, causing rotation of the movable sleeve 6′.

Like the first example of the administration mechanism, the deliverymember cover 5′ has a distal end portion 5 a′ and a proximal end portion5 b′. The proximal end portion 5 b′ has a generally tubular shape, andthe distal end portion 5 a′ has two legs 5 f. The delivery member cover5′ is configured to receive the movable sleeve 6′. The movable sleeve 6′is configured to be arranged between the two legs 5 f.

The delivery member cover 5′, in particular the distal end portion 5 a′has a cut-out 5 e′ having an open end in the circumferential direction.The cut-out 5 e′ has an axially extending elongated portion. Thedelivery member cover 5 furthermore has a through-opening 5 i′ axiallyaligned with and distally arranged from the cut-out 5 e′.

The delivery member cover 5′ furthermore has an end face 5 c′ whichdefines a guide surface 5 d′. According to the present example, the endface 5 c′ is a slanting or oblique with respect to the axial directionof the administration mechanism 23′. The slanting end face 5 c′ definesan angle relative to the longitudinal axis of the movable sleeve 6′ ofless than 90 degrees.

The movable sleeve 6′ has a radially outwards extending first followerstructure 6 a′. According to the present example, the radially outwardsextending first follower structure 6 a′ is a circumferentially extendingrib. The guide surface 5 d′ is configured to cooperate with the radiallyoutwards extending first follower structure 6 a′ when the deliverymember cover 5′ is moved from the first position to the second position,causing rotation of the movable sleeve 6′.

The movable sleeve 6′ furthermore has a lock structure 6 c′ extendingradially outwards. The lock structure 6 c′ is provided proximally fromthe radially outwards extending first follower structure 6 a′. The lockstructure 6 c′ is furthermore arranged spaced apart from the radiallyoutwards extending first follower structure 6 a′ in the circumferentialdirection. The cut-out 5 e′ is disposed so relative to the lockstructure 6 c′ that the lock structure 6 c′ is received by the cut-out 5e′ when the movable sleeve 6′ is rotated by distal movement of thedelivery member cover 5′. Due to the elongated shape of the cut-out 5 e′the lock structure 6 c′ is movable in the cut-out 5 e′, once receivedtherein, when the delivery member cover 5′ is moved axially relative tothe movable sleeve 6′.

The movable sleeve 6′ furthermore has a proximally extending flexibletongue 6 d′ which is flexible in the radial direction. The lockstructure 6 c′ is provided on a proximal end portion of the proximallyextending flexible tongue 6 d′. As previously mentioned, the lockstructure 6 c′ is received by the cut-out 5 e′ when the movable sleeve6's is rotated, and the proximally extending flexible tongue 6 d′ isflexed radially inwards when the delivery member cover 5′ is returnedtowards the first position, causing the lock structure 6 c′ to movebelow the inner surface of the delivery member cover 5′, until itreaches the distally located through-opening 5 i′, where it is flexedradially outwards and engages with the through-opening 5 i′. Thedelivery member cover 5′ will thus be locked in the first position.

Since the distal end portion 5 a′ is weakened mechanically by thecut-out 5 e′, which is disposed proximally of and axially aligned withthe through-opening 5 i′, the distal end portion 5 a′ functions as adamper in the event that the medicament delivery device in which itinstalled is dropped and the delivery member cover 5′ impacts a rigidsurface. The impact will thus be dampened, reducing the risk of the lockstructure 6 c′ disengaging from the through-opening 5 i′.

It shall be noted that the movable sleeve 6′ operates in the same manneras the movable sleeve 6 concerning interaction with the plunger rod,which is released when the movable sleeve 6′ is rotated, and thisfunctionality will therefore not be disclosed any further for thepresent example.

The operation of the administration mechanism 23′ will now be describedwith reference to FIGS. 7 a -7 e.

In FIG. 7 a the delivery member cover 5′ is in a first position relativeto the movable sleeve 6′, corresponding to the extended positionrelative to the housing, when installed inside a housing. FIG. 7 b showsthat the delivery member cover 5′ is being moved in the distal directionfrom the first position towards the second position relative to themovable sleeve 6′. In FIG. 7 c , the guide surface 5 d′ of the end face5 c′ is cooperating with the radially outwards extending lock structure6 a′, causing rotation of the movable sleeve 6′ as the delivery membercover 5′ is being moved in the distal direction. The lock structure 6 c′is being received by the cut-out 5 e′.

In FIG. 7 d , the delivery member cover 5′ has reached the secondposition relative to the movable sleeve 6′, corresponding to theretracted position relative to the housing, and the lock structure 6 c′has been moved to a proximal end of the cut-out 5 e′. In FIG. 7 e , thedelivery member cover 5′ has been returned to the first position, andthe lock structure 6 c′ has moved along the cut-out 5 e′ and snappedinto the through-opening 5 i′. The delivery member cover 5′ is henceprevented from being moved towards the second position.

The inventive concept has mainly been described above with reference toa few examples. However, as is readily appreciated by a person skilledin the art, other embodiments than the ones disclosed above are equallypossible within the scope of the inventive concept, as defined by theappended claims.

The invention claimed is:
 1. An administration mechanism for amedicament delivery device, where the administration mechanismcomprises: a movable sleeve comprising: an outer surface, a followerlocated on the outer surface, and a lock extending radially from theouter surface and configured to flex radially inward; a delivery membercover having a longitudinal axis and comprising a distal portion havinga guide surface, where the delivery member cover is configured to beaxially displaceable relative to the movable sleeve between a firstposition, a second position and a third position; and a first resilientmember that biases the delivery member cover in a proximal direction,wherein the distal portion of the delivery member cover engages andpushes the lock radially inward as the delivery member cover movesrelative to the moveable sleeve, wherein the guide surface comprises anend face that is slidably engaged with the follower when the deliverymember cover moves from the first position to the second position. 2.The administration mechanism of claim 1, wherein the guide surface isoblique with respect to the longitudinal axis of the delivery membercover.
 3. The administration mechanism of claim 2, wherein the obliquesurface defines an angle that is less than 90 degrees as measuredrelative to the longitudinal axis.
 4. The administration mechanism ofclaim 1, wherein the follower comprises a radial projection.
 5. Theadministration mechanism of claim 1, wherein the follower is acircumferentially extending rib projecting outward from the outersurface of the movable sleeve.
 6. The administration mechanism of claim1, wherein the lock is positioned on a tongue that is defined by acut-out in the outer surface of the moveable sleeve.
 7. Theadministration mechanism of claim 6, wherein the tongue flexes radiallyinward relative to the outer surface and then flexes radially backoutward as the delivery member cover moves from the first position tothe second position and then to the third position.
 8. Theadministration mechanism of claim 1, wherein the moveable sleeve rotatesrelative to the first resilient member when the delivery member covermoves from the first position to the second position.
 9. Theadministration mechanism of claim 1, wherein the distal portion of thedelivery member cover comprises a leg extending distally from a proximalportion of the delivery member cover such that an inside surface of theleg covers a proximal part of the outer surface.
 10. The administrationmechanism of claim 9, wherein the lock moves relative to the insidesurface of the leg when the delivery member cover moves from the firstposition to the second position and from the second position to thethird position.
 11. The administration mechanism of claim 9, wherein theinside surface of the leg engages and pushes the lock radially inward asthe delivery member cover moves relative to the moveable sleeve.
 12. Theadministration mechanism of claim 1, wherein the lock prevents axialmovement of the delivery member cover relative the moveable sleeve whenthe delivery member cover is in the third position.
 13. Theadministration mechanism of claim 1, wherein the lock engages the distalportion of the delivery member cover after the delivery member cover hasmoved to the third position.
 14. An administration mechanism for amedicament delivery device, where the administration mechanismcomprises: a movable sleeve comprising: an outer surface, a followerlocated on the outer surface, and a lock positioned on a flexible tongueand extending radially from the outer surface; a delivery member coverhaving a longitudinal axis and comprising a distal portion having aguide surface, where the delivery member cover is configured to beaxially displaceable relative to the movable sleeve between a firstposition, a second position and a third position; and a first resilientmember that exerts a proximally directed biasing force on the deliverymember cover during movement of the delivery member cover from the firstposition to the second position and to the third position, wherein aninside surface of the distal portion engages and pushes the lock andtongue radially inward as the delivery member cover moves relative tothe moveable sleeve, and wherein the guide surface is oblique withrespect to the longitudinal axis of the delivery member cover andcomprises an end face that is slidably engaged with the follower whenthe delivery member cover moves from the first position to the secondposition.
 15. The administration mechanism of claim 14, wherein the lockprevents axial movement of the delivery member cover in a distaldirection relative the moveable sleeve when the delivery member cover isin the third position.
 16. The administration mechanism of claim 14,wherein the lock has an oblique surface configured to cooperate with theinside surface of the delivery member cover.
 17. The administrationmechanism of claim 14, wherein the lock and the distal portion form asnap lock function when the delivery member cover is in the thirdposition.
 18. The administration mechanism of claim 14, wherein theguide surface is a cam surface.
 19. A medicament delivery devicecomprising: a housing; an administration mechanism, where theadministration mechanism comprises: a movable sleeve comprising: anouter surface, a follower located on the outer surface, and a lockextending radially from the outer surface and configured to flexradially inward; a delivery member cover having a longitudinal axis andcomprising a distal portion having a guide surface, where the deliverymember cover is configured to be axially displaceable relative to themovable sleeve between a first position, a second position and a thirdposition; and a first resilient member that biases the delivery membercover in a proximal direction, wherein the distal portion of thedelivery member cover engages and pushes the lock radially inward as thedelivery member cover moves relative to the moveable sleeve, wherein theadministration mechanism is positioned within the housing such that thedelivery member cover is rotationally fixed relative to the housing; anda hollow plunger rod containing a proximal portion of a second resilientmember that biases the plunger rod proximally, wherein in the firstposition the delivery member cover is configured to extend from aproximal opening of the housing, and wherein the delivery member coveris configured to be rotationally locked relative to the housing, whereinthe moveable sleeve rotates relative to the first resilient member whenthe delivery member cover moves from the first position to the secondposition.